A DSL (digital subscriber line) is a high-speed data transmission technology for transmission by telephone twisted pairs. Generally, DSL services are provided for multiple subscribers in a bundle of cables. A system providing multi-channel DSL access is called DSLAM (access multiplexer). Due to the electromagnetic induction principle, crosstalk may be mutually generated among multiple channels of signal received by the DSLAM, which causes problems such as a low line speed, unstable performance, and even a service provisioning failure. Currently, a DSL vectoring technology is mainly used to perform receiving and transmission in a united manner on the multiple channels of signal at a DSLAM end, and a signal processing method is used to eliminate the crosstalk.
In a DSL vectoring system, an initialization process includes multiple downstream vectoring steps and upstream vectoring steps; a subscriber line needs to pass through the foregoing vectoring steps (that is, a joining state) to ultimately reach an online state. When there is a subscriber line that is already in a joining process, other subscriber lines can join the DSL vectoring system until the subscriber line that is joining the DSL vectoring system reaches the online state. An ideal condition is that all subscriber lines pass through the vectoring steps together and reach the online state at the same time, and each subscriber does not need to wait other subscribers. However, actually, there is a low probability that all subscriber lines join a DSL vectoring system at the same time; as a result, the subscriber line that joins the DSL vectoring system later needs to wait for relatively long time. In addition, a common resource of the system is wasted.